Method of producing a felted textile material



July 16, YUK|CH| GO METHOD OF PRODUCING A FELTED TEXTILE MATERIAL Filed June 29, 1964 A l *MUM muss/N6 Tn e,

United States Patent O 3,393,083 METHOD F PRODUCING A FELTED TEXTILE MATERIAL Yukichi Go, 693-85 Oaza Tashiro, Tsumakoi-mura, Agatsumagun, Gumna, Japan Filed June Z9, 1964, Ser. No. 378,764 6 Claims. (Cl. 117-10) The present invention relates to feltable fibers land a method of making the same and, more particularly, the present invention is concerned with imparting to fibers other than wool, a more or less wool-like surface pattern.

According to the present invention feltable fibers are provided which have an asymmetric fine surface pattern or scales or serrations of very small dimensions.

Various methods have been proposed for applying the shape of wool to fibers other than wool. According .to some of these methods, wool-shaped curls are given to the fibers by mechanical deformation or heat treatment.

It is .an object of the present invention to provide fibers other than wool, and which may be natural or synthetic fibers, with an .asymmetric finesurface pattern or scales or serrations.

It is another object of the present invention to provide feltable fibers other than wool of improved spinnability and which may be subjected to a fulling process, for instance when it is desired to make of such fibers a papermakers felt or an ordinary felt.

It is a further object of the present invention to provide a non-wool fiber and la method of making thesame, which fiber has a surface configuration substantially like that of natural wool and, consequently, possesses characteristics which are substantially similar to` those of wool.

It is yet another object of the present invention to provide a textile material having properties substantially similar to that of Wool but rbeing less susceptible t-o shrinkage upon washing.

Other objects and advantages of the present invention will become apparent from a further reading of the description and of the appended claims.

With the above and other objects in view, the present invention includes a feltable fiber, tat least the outer portion of which consists of synthetic material, said outer portion having in longitudinal section a substantially sawtooth configuration with the inclined surfaces of each tooth defining substantially different angles with the axis of the ber so that when the fiber is pulled in one longitudinal direction along a given surface, the coefficient of friction will be substantially different from the coeicient of friction when the fiber is pulled in the opposite longitudinal direction.

The present invention is lalso concerned with .a method of producing a feltable fiber, comprising the steps of forming on a fiber a coating adapted to be deformed when in softened condition, softening the coating, forming in the softened coating a plurality of indentations so as to give to the outer face of the coating in longitudinal section a substantially saw-tooth configuration with the inclined surfaces of each tooth defining substantially different angles with the axis of the fiber, and hardening the thus deformed coating thereby obtaining a coated fiber which whe-n pulled in one longitudinal direction along a given surface has .a coefficient of friction which is substantially different from the coefiicient of friction obtained when the coated fiber is pulled in the opposite direction.

According to the present invention, a feltable liber may be produced from a fiber which does not possess feltable characteristics, by covering or coating the surface of the fiber with a material which may be deformed so as to produce a desired surface pattern on the coating rand thus on the fiber. The thus coated fibers are then arranged parallel to each other and the coating is rendered deform- 3,393,083 Patented July 16, 1968 ICC able, for instance by heating if t-he coating consists of a thermoplastic material, or vby treating the coating with a liquid which will cause swel-ling of the coating. The thus arranged coated fibers are then embossed, preferably by being passed between embossing rollers, so as to engrave a fine asymmetric surface pattern on the surface of the fibers, and the thus treated fibers may Ithen be subjected to elongation, heat treatment, or cutting, depending on .the qualities required of the final product.

The process may be started either with filaments or with a strip or film. When treating filaments such as rayon or synthetic fibers according to the present invention, t-he filaments are first arranged parallel to each other and then rare coated with a solution of the material in which the serrations are to be formed, or with such material in molten state. Coating is carried out by passing the long filaments parallel .to each other through the solution or melt and then between embossing rollers which will emboss the saw-tooth pattern into `the coating. If the coating hasl been applied in the form of fa solution, the embossing r-ollers or scale printers .are preferably heated so that simultaneously with forming the saw-tooth pattern on the filaments, the solvent is evaporated. If the coating has been applied in molten state, embossing is carried' out with cold rollers, so that simultaneously with embossing the saw-tooth pattern, the coating will be solidified.

In either case, the filaments, with the saw-tooth pattern embossed in the coating thereon, are then cut into staple fibers and upon subsequent spinning of the staple fibers wool-like filaments are obtained.

When carrying out the process with a unitary single film having a thickness of for instance between 5 and 10 microns, coating of the film strip is carried out substantially in the same manner as in the case of the parallel filaments. The coated strip is then embossed by being passed between the embossing rollers and thereafter cut into filaments having a width of, for instance, between 5 and 10 microns. The thus obtained filaments are then cut into staple fibers.

It is also possible and sometimes advantageous to start with a laminated film consisting of two films having different heat contraction ratios, for instance, in a direction perpendicular to the longitudinal extension of the strip, or so that the direction of the heat contraction of one of the films is somewhat biased against the longitudinal direction of the strips. In the first case, when cutting the embossed film in a direction perpendicular to the longitudinal extension of the film, and subjecting the film or the staple fibers to heat treatment, fibers having a configuration such as shown in FIG. 5 will be obtained. In the second case, i.e., when the direction of heat contraction of one of the films of the laminated film is biased against the longi tudinal extension of the film strip, a spirally curled staple fiber will be obtained.

. .The surfa-ce of wool fibers is formed of scales or serrations which have a depth of several thousands of a millimeter and a pitch of several hundreds of a millimeter. The more or less saw-tooth-like cross sectional configuration of the wool fiber surface is characterized by the difference between the two surfaces of each tooth, each of which is inclined under a substantially different angle to the axis of the fibers. These angles are described herein as angles a and whereby, as will be shown, the angle is greater than the angle a.

Due to the difference of these two angles, the coefficient of friction when pulling the fiber along a given surface in one axial direction of the fiber will differ from the coefficient of friction when the fiber is pulled in the opposite direction.

When fibers of this type are subjected to the so-called fulling process in water, felting can be effected so as to obtain better spinnability.

According to the present invention, a more or less woollike surface pattern can be produced on other fibers, as will be described in more detail below, by embossing the deformable surface of such other fibers by passing the same between embossing rollers having a surface pattern corresponding to that which is to be imparted to the fibers. Such surface pattern is preferably produced on a plate or sheet which will then form the surface of the embossing roller, by means of a diamond cutter and a ruler arrangement, such as is used for producing a spectro-interference grating. The angles a and of the cutter and the pitch, i.e., the distance between the adjacent lines can be adjusted so as to have a desired relationship to the diameter of the filament or fiber which is to be embossed.

An asymmetric fine saw-tooth-like surface can be ernbossed on a plurality of parallelly arranged fibers or on film consisting of fiber material, provided that the surface portions which are to be embossed are in deformable condition, for instance, at an elevated temperature in the case of thermoplastic material, or in a swollen condition in the case of material which is adapted to swell when treated with water or another suitable liquid.

The fibers which are thus produced may be used as they are obtained, or may be cut into shorter staple fibers of desired length, after the uncut fibers may have been subjected to elongation. In this manner, feltable fibers having an assymmetric fine surface pattern or scales or serrations will be obtained.

According to the present invention, the deformable surface of either a fiber or a film consisting of a fiber forming material, or the surface portion of such fiber or film which is deformable, is subjected to pressing while in softened or plasticized condition, due to a thermal or swelling treatment, so that the above described asymmetric, fine pattern can be impressed or embossed on the surface of such fiber or film.

The thus embossed bers may be cut into desired lengths or the thus embossed film may be continuously cut into fine ribbons so as to form fibers thereof and, if desired, subjected to a setting process by twisting, or cut into short staple fibers ready for felting.

After the fulling process has been finished, the deformable material with which the fibers or film has been coated and in which the desired asymmetric, saw-toothlike pattern has been embossed, may be dissolved and thus removed, or, preferably, only the outer portion thereof, i.e., the saw-tooth-like sharp edges which might cause shrinkage upon subsequent washing may be destroyed or removed.

For instance, a laminated film of two fibrous materials having different shrinkage rates depending on outside conditions, such as temperature, swelling, etc., may be used. In this case, short hollow fibers having scales or serrations formed around their entire surface can be obtained by cutting the film into staple fibers and subjecting the films or fibers to heating, swelling, etc., thereby curling the ribbon-shaped fibers into concentric cylindrical shapes. The composite or laminated film gives anistropy to the shrinkage rate of the fiber and thus spiral shrinkage may lbe given to the film.

If it is necessary to completely remove the asymmetric surface pattern making material after fulling process has been effected, for instance for dyeing, etc., a curve or spiral pattern should be set as it is. However, when the scale making material is made substantially as thick as possible, and the material is dissolved by a solvent for the surface pattern making material, or the fine, asymmetric pattern is either destroyed or taken away by heat treatment, swelling, chemical treatment (treatment by acid or alkali), the pattern can be removed. Furthermore, when the lm consisting of the fibrous material is made of two layers, i.e., the film layer having the different degree of pre-elongation and direction has been laminated, the pattern setting process can be omitted even if it is necessary to completely dissolve the surface pattern making material. The fiber having such construction can be adjusted in such a manner that it may exhibit the optimum shrinkage pattern by means of the outside conditions or other treatment during each step such as spinning, weaving, knitting, fulling or finishing.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its ymethod of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a schematic elevational cross-sectional view illustrating the making of an embossing plate for forming the saw-tooth pattern on fibers and films, according to the present invention;

FIG. 2 is a schematic elevational view illustrating the embossing of fiber or film material between rollers having 4a cylindrical surface formed as illustrated in FIG. l;

FIGS. 3 and 4 are schematic cross-sectional views of fiber portions having the surface pattern formed laccording to the present invention; an-d FIG. 5 is a View of a feltable fiber of laminated film in accordance with the present invention.

Referring now to the drawings, and particularly to FIG. l, a diamond cutter 1 is shown having a cutting edge formed of two planes which extend at angles a and I3 respectively to the longitudinal direction of a sheet 2 in which the pattern is to be engraved. The sheet may be, for instance, of aluminum, copper, suitable plastic, glass or the like. The indentations are formed at the desired pitch l and with the desired depth d' by shifting plate 2 and cutter 1 relative to each other after the forming of each groove. The thus formed pattern plates are then placed on the surface of embossing rollers 3 and 3', as shown in FIG. 2, and 4the fibers 4 with their surface in plasticized condition are then passed between the toothed rollers 3 and 3', as indicated by the arrows, so las to form the embossed fiber 4. The grooves or teeth of the em- -bossing rollers may extend at a right angle or at an acute angle against the fibers passing between the rollers.

The minimum value for ,8 will be about It is technically difficult to cut so that will be less than 90. When d is determined first, the pitch will depend primarily on angle a. The optimum values for the pitch and the depth of the serrations will `depend on the thickness of the fibers, elasticity, density of the assembly, crimpness, degree of deformation -during the fulling process and other variables.

As shown in FIG. 3, in this manner, for instance, a synthetic fiber is formed having a saw-tooth surface configuration with the two inclined surfaces of each tooth defining substantially different angles a and IS with the axis of the fiber. The grooves between the individual teeth have a ydepth d1 which will be chosen in the proper relationship to the diameter d2 of the fiber.

FIG. 4 illustrates a composite fiber, according to the present invention, wherein the fiber 5 is covered with a coating 6 in which the saw-tooth configuration is formed. The diameter `of the inner fiber is indicated as d2 and the maximum thickness of the coating :as d2. Here again, the two inclined surfaces of each tooth define substantially different angles a and ,B with the axis of the fiber.

In FIG. 5 reference numerals S and 6 represent the two film-shaped fi-brous materials of -a laminated film cut to staple fibers and curled due to their different thermal expansion coefficient, swelling behavior or the like, which will bend internally so that asymmetric fine surface portions or scales are maintained along the entire periphery and a rounded substantially hollow fiber is formed.

-By embossing -a polyethylene film with the saw-toothshaped pattern so that angle a will be between 25 and 35, angle between 115 and 120, l will indicate a asaaosa `length of 22. microns, d1 equals l0 microns, cutting the film into strips of a width of 1 mm. and comparing the thus formed fibers with naturalwool, the following friction coefficients are found:

. lnthe above table ,uw and ,ua are the friction coefficients in the two opposite longitudinal directions of the fibers which are determined with a conventional friction Lcoefficient tester. The dynamic friction coefficient is Obtained at a velocity of 30 cm. per minute.

. The friction coeflicient may be tested with the Single Fiber Friction Tester manufactured by Aoi Fine Scientific Instrument Research Laboratory, Kyoto, Japan, as described in lan article entitled, On the Determination of Friction Coefficient of Fiber by Takahashi & Koshimura, which appeared in the Journal of the Textile Machinery Society, 8, 262, 1955.

The test results shown above indicate the remarkable difference in the friction coefficient along the two opposite longitudinal directions of the fiber which makes it possible to subject the fiber of the present invention to substantial fulling, to felt the fiber as desired and to produce mixed yarns of fibers according to the present invention and wool which mixed yarns for any given proportion of wool therein will have a -better spinnability as could be heretofore achieved with mixed yarns.

Without depending on any specific theory of the fulling process it appears that when the felting or fulling process is carried out with the assembled filaments of the present invention or with wool, various severe deforma- -tions such as compression, stretching, bending, shearing,

etc., occur repeatedly When the filaments within the aS- sembly lare subjected to friction at their contact points.

v When the friction coeiiicient differs in opposite directions of the filament, as is the case with natural wool or with fibers formed according to the present invention, there will be a somewhat more extensive movement of the filaments in the direction of the lesser friction coefficient. As a resulted, the filaments are entangled with each other so =as to increase the density of the assembly or fabric, tO contract or reduce the volume of the assembly and thus to proceed with the felting or fulling process as desired. The difference of the friction coefficient in opposite axial directions of the filament is caused by the asymmetric saw-tooth pattern of the surface of the filament. At the same time, the saw-tooth pattern also increases the absolute value of the friction coefficient so as to give better spinnability, to prevent the separation of the filament after spinning and to improve the quality of the spun fiber.

For instance, it is possible to mix synthetic fibers, for instance, nylon, which has been treated according to the present invention, in a relatively very large proportion with Wool and thereby to greatly increase the durability of the thus obtained yarn.

It is also possible to mix chemical fibers, synthetic fibers or mixed yarns containing a proportion of fibers treated according to the present invention, `:into ordinary wool fabric.

The fibers or fibrous materials on which the saw-tooth pattern can be directly formed, according to the present invention, include regenerated cellulose, cellulose acetate, nylon, vinylon, polyester synthetic fibers, polyacrylic synthetic fibers, polyolefin fibers such as polyethylene and polypropylene fibers, polyurea fibers and polyamino acid fibers, as well las various other materials which are suitable for forming fibers and which can be rendered deformable. Y

All of the above materials may also be usedfto form the coating on fibers of, for instance, silk, cotton, hemp or other animal or vegetable fibers which have no scales or serrations.

Furthermore, for forming the -coating on the fibers in which the saw-tooth pattern is to be embossed or engraved, also other materials, such as polyvinyl alcohol, alginic acid and soluble cellulose derivatives may be used, particularly when subsequently the surface pattern is to be at least partially removed by dissolution, heat treatment'or chemical treatment, after the fulling step has been carried out.

The washing of woven or knitted woolen material or textiles formed of fibers according to the present invention results in'repeated severe deformation in water or weak alkali and is thus comparable to the fulling process. Thus, fullirigproceeds further during the washing of fabrics made of feltable fibers so that the density of the fabric is increased and the thus washed fabric is contracted. This is a great disadvantage of woolen fabrics. The saw-tooth pattern, once the felting or fulling process is completed is no vlon-ger necessary and it is desirable to dissolve at least partially the ser-rations or saw-tooth pattern at this point.

Such removal of the pattern can be carried out by dissolution or chemical treatment, or the pattern may be destroyed without complete removal of the coating by heat treatment, swelling or chemical treatment.

The Isaw-tooth pattern t-hus may be removed so as to eliminate the sharp edges and the difference of the friction coefficient in opposite axial directions, so that a wave like alternatingly concave and convex undulating surface pattern remains. In this manner the friction coefficient is maintained to a considerable extent but it will now be the same in both opposite :axial directions of the fibers. This is accomplished by applying a swelling agent so as to soften the surface pattern forming material during the final stage ofthe fulling process, or by applying a solvent, or by heat treatment. In either case, during the final stage of the fulling process, the asymmetry of the saw-tooth pattern is removed and replaced by an undulating surface configuration. Consequently, upon subsequent washing of the fabric, shrinkage will be greatly reduced or not occur at all, since as pointed out above, shrinkage during washing, felting or fulling is due to the difference in the friction coefficient in opposite axial directions.

Thus, lthe present invention provides a feltable fiber which has a fine, asymmetric surface pattern or scales or serrations which are so shaped that the friction coefficient in one direction of the axis of the fiber is markedly different from the friction coefficient in the opposite direction. Furthermore, such fibers, as described above, are provided, according to the present invention, wherein the surface pattern can be completely or partially removed by, for instance, dissolution or any ofthe other treatments described herein, for inst-ance, after the felting step has been completed.

The present invention also is concerned with a method of making a feltable fiber of fiber which per se does not render itself to fulling and felting, by coating the surface of the fiber with a material in which the above described saw-tooth pattern can be formed, arranging the thus coated fibers parallel to each other and passing the same 'while lt-he coating material is in deformable condition through embossing rollers, either in a direction perpendicular to or under an acute angle to the axis of the fibers.

The thus embossed fibers may then be subjected to elongation, heat treatment or cutting, depending on the desired further use.

Wit-hout further analysis, the fore-going |will so fully reveal the gist of the present invention that 'others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint 'of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and ran-ge of equivalence of the following claims. i

What is claimed as new and desired to be secured by Letters Patent is:

1. A method of producing a felted textile material,

comprising the steps of fonming on a fiber a coating adapted to be deformed when in softened condition; softening said coating; forming in said softened coating a plurality of indentations so as to give to the outer face of said coating in longitudinal section a substantially sa'wtooth configuration with the inclined surfaces of each tooth defining substantially different angles with the axis of said fiber; hardening the thus deformed coating thereby obtaining a coated fiber which when pulled in one longitudinal direction along a given surface has a coefficient of friction which is substantially different from the coefficient of friction obtained when said coated fiber is pulled in the opposite direction; subjecting a plurality of the coated fibers to rfelting so as to form a felted textile material; and thereafter at least partially removing said coating from the fiber of the thus formed felted textile material.

2. A method of producing a felted textile material, comprising the steps of forming on substantially smooth fibers a removable surface layer having an irregular outer surface the latter imparting to said fibers a coefficient of friction which is different depending on the direction in Iwhich the fiber is pulled; felting a plurality of said fibers Iwith said removable surface layer thereon so that the rough surfaces of said removable surface layers of said fibers interengage thereby facilitating forming of a loose felted material; and thereafter removing said surface layers from the thus fonmed felted material.

3. A method of producing a felted textile material, comprising the steps of forming on smooth fibers a removable coating having an irregular outer surface the latter imparting to said fibers a coefficient of friction which is different depending o-n the direction in which the fiber is pulled; felting a plurality of said fibers with said removable coating thereon so that the irregular surfaces of said removable coatings of said fibers interengage thereby facilitating forming of a loose felted material; and removing said 'removable' coating from the,thus formed felted material.-` l.

4. A method as defined in claim 3, wherein said irregular outer surfaces of said coatings are in longitudinal .section of substantially saw tooth configuration with the inclined surfaces of each tooth defining substantiallvdifferent angles rwith the axes of said fibers, respectively.

5. A method as defined in claim 4, wherein said coating on said fibers is formed by applying to said fibers a coating adapted to be deformed when in softened condition; forming in said coating 'while the same is insoftened condition a plurality of indentations so as to givetothe outer face of said coating said `substantially saw-tooth configuration; and hardening the thus deformed coating, thereby obtaining afcoated -fiber which :when pulled in one longitudinal directiony along a given surface has a coefiicient of friction which is substantially different'from the coefficient of friction of said coated yfiber 'when the same is pulled in the opposite. longitudinal direction.

6. A method of producing a felted textile material as defined in claim 3, 'wherein said smooth fibers are selected from the group consisting of regenerated cellulose fibers, cellulose acetate fibers, nylon fibers, polyester fibers, polyacrylic fibers, polyolefinic fibers, and polyurethane fibers. i

References Cited UNITED STATES PATENTS 2,200,946 5/1940 '1316611 161f-179 2,866,256 12/1958 Marlin 161-179 3,015,873 1/1962 Dietzsch etal. 161-175 3,112,160 11/196-3- Rush y161--180 3,127,915 4/1964 Bottomley 1611-179 3,243,339 3/1960 scragg et ai.' 161-179 FOREIGN PATENTS 973,159 2/1951 France 161-179 MURRAY KATZ, Primary Examiner'. 

1. A METHOD OF PRODUCING A FELTED TEXTILE MATERIAL, COMPRISING THE STEPS OF FORMING ON A FIBER A COATING ADAPTED TO BE DEFORMED WHEN IN SOFTENED CONDITION; SOFTENING SAID COATING; FORMING IN SAID SOFTENED COATING A PLURALITY OF INDENTATIONS SO AS TO GIVE TO THE OUTER FACE OF SAID COATING IN LONGITUDINAL SECTION A SUBSTANTIALLY SAWTOOTH CONFIGURATION WITH THE INCLINED SURFACES OF EACH TOOTH DEFINING SUBSTANTIALLY DIFFERENT ANGLES WITH THE AXIS OF SAID FIBER; HARDENING THE THUS DEFORMED COATING THEREBY OBTAINING A COATED FIBER WHICH WHEN PULLED IN ONE LONGITUDINAL DIRECTION ALONG A GIVEN SURFACE HAS A COEFFICIENT OF FRICTION WHICH IS SUBSTANTIALLY DIFFERENT FROM THE COEFFICIENT OF FRICTION OBTAINED WHEN SAID COATED FIBER IS PULLED IN THE OPPOSITE DIRECTION; SUBJECTING A PLURALITY OF THE COATED FIBERS TO FELTING SO AS TO FORM A FELTED TEXTILE MATERIAL; AND THEREAFTER AT LEAST PARTIALLY REMOVING SAID COATING FROM THE FIBER OF THE THUS FORMED FELTED TEXTILE MATERIAL. 